So is divorce ( except under strict conditions). Jesus said that if someone divorces their partner and remarries they commit adultery.
Is the church saying to all the people on their 2nd, 3rd or even more marriages that they need to repent? Are they being asked to annul those marriages and go back to their first husband or wife, or to remain single?
If not, then why make allowances for one group of people but not another?? As you say, God makes the rules.
You turning from your sin should not be contingent on whether other people turn from theirs. At the end of the day, you can only turn from and be cleansed of yours.
I repent when I fall short. Whether others are told to repent for other things does not determine whether I decide to ask for forgiveness for my thing and act in accordance with what God wants.
Take it from me; I came out of the LGBT life when I received Christ. It's not impossible and no excuses should be made for the LGBT community.